1 Answer. Since sub is a prefix, it must be connected to the word, at least by a hyphen. So sub district is out.

How do you spell sub district?

A subdistrict or sub-district is an administrative division that is generally smaller than a district.

What subdistrict means?

subdistrict. / (ˈsʌbˌdɪstrɪkt) / noun. a smaller part of a larger area marked off for administrative or other purposes.